Yet another way germ theory changed how we think about health.
Pandemics at the scale of COVID-19 are relatively seldom—thankfully—but when they happen, they leave their mark on society for years to come. They shake up everyday lives, demand new habits, and introduce new vocabulary. If COVID-19 has taught people any new phrase, it’s social distancing.
Social distancing—or the practice of keeping space between you and others to reduce the spread of contagious respiratory infections—is a relatively new phrase, but the concept is centuries old. As with many aspects of public health, social distancing can be traced back to germ theory.
The Early Days of Public Health
Before germ theory, societies handled diseases in a variety of ways—some effective, some ineffective. When things were effective, such as isolating sick people, they were repeated and shared with other cultures, even if nobody could explain why it worked.
Pandemics and plagues were believed to be punishment for sinning, so strategies often revolved around “morally purifying” societies. For example, the Old Testament mentions isolating people with a skin disease (which is now believed to be leprosy). However, isolation was more of a punishment; leprosy caused disfigurement, which created a stigma that people with the disease were unclean or morally impure, and they should be separated from others so they couldn't spread their sin.
Isolation in the name of public health emerged more during the bubonic plague. The “Black Death” started in China in the 1300s, and it spread to every continent within 5 years via trade routes. The bubonic plague was a devastating pandemic that occurred in several “waves” that lasted for centuries.
The first known “quarantine” occurred in 1377. In Ragusa, Italy—a city on the island of Sicily—a law went into effect that anyone who wanted to enter the city had to be isolated on a nearby island for 40 days first. In fact, quarantine comes from Italian for “forty days.”
This quarantine—long before infectious diseases were understood—was one of the only successful attempts to curb the bubonic plague, so its use became popular throughout Europe.
When quarantine measures were disregarded, results could be devastating. In 1720, local merchants in Marseille pressured authorities to release a cargo ship from quarantine after just 10 days or so; when the crew and cargo entered the city, an outbreak erupted in Marseille and killed 60,000 of its inhabitants.
Social Distancing During the 1918 Flu
Public health measures during the bubonic plague targeted travelers, as well as those who were already visibly infected. When the 1918 flu pandemic came around, and public health experts were armed with the knowledge of germ theory and how influenza spread, tactics shifted: Social distancing measures were finally employed.
In the United States, many cities closed places like schools, churches, and theaters. Some cities banned large gatherings, some mandated face masks, and some required staggered shifts in factories. (Sound familiar?)
Social distancing clearly had an effect: The cities who acted sooner and more strictly (such as St. Louis, which implemented social distancing measures within two days of the first reported cases) had lower peak mortality rates. By contrast, cities like Philadelphia waited two weeks to enact social distancing, and their peak mortality rate was eight times higher than that of St. Louis.
Social Distancing in the 21st Century
It may not have captured the attention of many Americans, but the 2009 H1N1 pandemic also embraced social distancing. In April 2009, President Obama gave a press conference and recommended that schools with confirmed or suspected cases of H1N1 influenza close temporarily, and businesses and parents should "think about contingency plans if their children do have to stay home." Additionally, the World Health Organization recommended social distancing, which they defined as “keeping an arm’s length distance from others.”
During the COVID-19 pandemic, however, this recommendation for social distancing was expanded to 6 feet (or 2 arms’ length) since that is how far infectious respiratory droplets can travel when someone coughs or sneezes. Similar to the 1918 flu pandemic, cities have also mandated face masks, closed gathering spaces, and banned large events. Learn more about social distancing guidelines for COVID-19.
As for quarantine, it’s still used, especially for those who are infected, have traveled, or have been exposed to someone who was infected. Instead of being held in ships or on islands, however, people are typically asked to not leave their homes. (Learn more about the difference between quarantine, isolation, and social distancing here.)
Still, social distancing has become a fixture of public health strategies because—for many infectious diseases—people can be contagious before showing symptoms. In the case of COVID-19, people can be infected without ever showing symptoms at all, meaning they are "asymptomatic carriers." Social distancing reduces the close contact of people, thus giving the virus fewer opportunities to jump from one person to another when so many people do not know their own infection status.
The Predictable Challenges of Social Distancing
Even when history provides statistics that something works, the hardest part of enacting social distancing is getting people to cooperate. “Unfortunately, along with outbreaks, a recurring pattern of societal amnesia has prevailed,” writes Frank M. Snowden in the preface to his book Epidemics and Society: From the Black Death to the Present—published in 2019 but updated following the outbreak of COVID-19
According to Snowden, countries often create preparedness plans in the years following devastating pandemics, but as time passes, everyone quickly reverts to “business as usual,” funding for pandemic prevention is ditched, and prevention agencies are disbanded.
When a pandemic hits, many people are struck with disbelief that something like this could happen and flip their lives upside down. “A more fitting question is whether, after COVID-19 abates, the world will return to complacency or decide upon a sustainable, long-term assessment of the likely challenges and organize the means to meet them,” writes Snowden.
Drews K. A brief history of quarantine. Virginia Tech Undergraduate Historical Review. 2013 May 1. (Accessed on May 6, 2020 at https://vtuhr.org/articles/10.21061/vtuhr.v2i0.16/.)
History of quarantine. Atlanta, GA: Centers for Disease Control and Prevention, 2012. (Accessed on May 6, 2020 at https://www.cdc.gov/quarantine/historyquarantine.html.)
History of quarantine. PBS. (Accessed on May 6, 2020 at https://www.pbs.org/wgbh/nova/typhoid/quarantine.html.)
Huremovic D. Brief history of pandemics (pandemics throughout history). Psychiatry of Pandemics. 2019 May 16:7-35.
Pandemic influenza prevention and mitigation in low resource communities. Geneva, Switzerland: World Health Organization, 2008. (Accessed on May 6, 2020 at https://www.who.int/csr/resources/publications/swineflu/PI_summary_low_resource_02_05_2009.pdf?ua=1.)
Rapid response was crucial to containing the 1918 flu pandemic. Bethesda, MD: National Institutes of Health, 2007. (Accessed on May 6, 2020 at https://www.nih.gov/news-events/news-releases/rapid-response-was-crucial-containing-1918-flu-pandemic.)
Social distancing, quarantine, and isolation. Atlanta, GA: Centers for Disease Control and Prevention, 2020. (Accessed on May 6, 2020 at https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/social-distancing.html.)
Snowden FM. Epidemics and society: from the Black Death to the present. New Haven, CT: Yale University Press, 2019.
The President’s remarks on H1N1. Washington, DC: The White House, President Barack Obama, 2009. (Accessed on May 20, 2020 at https://obamawhitehouse.archives.gov/blog/2009/04/30/presidentrsquos-remarks-h1n1.)
Tognotti E. Lessons from the history of quarantine, from plague to influenza A. Emerg Infect Dis. 2013 Feb;19(2):254-259.